Pakistan's former prime minister Imran Khan said on Saturday he expected to be arrested as he headed to court on graft charges, after days of legal wrangling and pitched battles between his supporters and police.

The 70-year-old former cricket star has been tangled in a slew of court cases, a frequent hazard for opposition figures in Pakistan's mudslinging politics.

Khan was ousted in a no-confidence motion last year and has been pressuring the fragile coalition government which replaced him to hold early elections.

"I am going to the Islamabad court right now. I want to tell you all that they have made a plan to arrest me," he said in a video message from the motorway, claiming he was the target of a plot to stop him from standing in elections due by October.

"The point of their attack on my house was not to present me before the Islamabad court. The purpose was to put me in jail."

Some 4,000 security officials including elite police commandos, anti-terrorism squads and paramilitary rangers have been deployed around Islamabad with hospitals put on high alert.

Police fired tear gas at supporters who had gathered at the court in anticipation of Khan's arrival, chanting and pelting stones and bricks at officers.

Earlier this week Khan's supporters fought pitched battles with police sent to arrest him in the eastern city of Lahore after he failed to appear in court, citing security concerns.

Authorities were later stood down after a flurry of court hearings and Khan's promise to appear in the capital on Saturday.

Police meanwhile raided his house in a plush Lahore neighbourhood after blocking nearby roads and suspending mobile services in the area.

The case has been brought by the Election Commission of Pakistan which has accused Khan of not declaring gifts received during his time as premier, or the profit made from selling them.

Pakistan's courts are often used to tie up lawmakers in lengthy proceedings that rights monitors criticise for stifling political opposition.

As the political drama unfolds, Pakistan is in the grip of a stark economic downturn, risking default if help cannot be secured from the International Monetary Fund.

The security situation is also deteriorating with a spate of deadly attacks on police, linked to the Pakistan Taliban.

Khan has been pressuring the coalition government that replaced him, led by Prime Minister Shehbaz Sharif, with popular rallies and daily addresses broadcast on social media.

Last year Khan was shot in the leg during a political rally, an assassination bid he blamed on Sharif. AFP